<?php
    session_start();
    function islogin(){

        if(isset($_SESSION['stu_num'])){
            return "stu_login";
        }
        if(isset($_SESSION['t_num'])){
            return "teacher_login";
        }
        if((!isset($_SESSION['stu_num']))&&(!isset($_SESSION['t_num']))){
            return false;
        }
    }
